Apparatus for effecting compound drying



May 4, 1937. E. A. LE SUEUR APPARATUS FOR EFFECTING COMPOUND DRYING Filed May 21, 1935 Patented .May 4, 1937 PATENT OFFICE ao'zaesz v APPARATUS FOR'EFFECTING COMPOUND I name Ernest Arthur L Sueur, Ottawa, Ontario, Canada Application May 21, 1935, Serial No. 22,634

3 Claims.

again. Also for isolating drying-equipment, andmaterial carried by same in process of being dried, in steam.

Further features will appear.

My said invention will be understood by reference to the drawing.

In this, Fig. 1 shows an apparatus in vertical longitudinal section; Fig. 2 is a plan; Fig. 3 an elevation of the left-hand end; Fig. 4 a crosssectional elevation on the line A-B of Fig. 1,

looking to the right, this figure omits internal conveying-apparatus shown in Fig. 1; Fig. 5 is an elevation of the right-hand end; Fig. 6 is a detail of an' endless-belt-operated member, carrying stirring-plows, shown broken; Fig. 7 a similar detail of another such member carrying similar plows with their positions transposed from those in Fig. 6; Fig. 8 shows one of many alternatives to the arrangement in Fig. 1 for compound defiectors for condensate. i With more particular reference to the draw- In said drawing, l is a chest adapted to receive hot fluid, 2 is the top member of same, its upper surface acts as a drying-floor for material, 3 is a pipe adapted to supply said fluid, and also, in

case of condensible vapor being used as the heating-medium, to permit condensate to drain downwardly; 4 is a. ventingpipe, also communieating with theinterior of said chest I; 5 is a valve in said pipe; 6 is a member the underside of which forms the ceiling of a chamber of which the member 2 is the floor, its upper side forms a floor adapted to carry material to be dried; I is a;member adapted to catch condensate which forms on the under side of. 6; 8, 8 are curbed holes in 1;" 9, 9 are deflectors above the holes 8 adapted to keep condensate from falling through thelatter; I0 is a trapped vent for condensate from said member I; II and I2 are passages leading downwardly from the left;hand and right-hand ends respectively of the above-mentioned chamber; l3, l3 are the pitch circles of pulleys, convenientlyfor link-belts, mounted on tlieshaft l4; l5 isa pulley on 14, driving connections not shown, adapted to turn said shaft; Hi, l6 are pulleys mounted on the shaft I'I. Two endless belts, I 8, l8, preferably link-belts, are mounted on l3, l3 and 16, It. In Fig. 1, only-the pitch line of these belts is shown; in Fig. 2, two short pieces of the lower sections of said belts are indicated,

details of the link-belting not shown; l9, I!) are idle pulleys, mounted on the shafts 20, adapted to support the upper sections of the belts l8; 2| and 22 are two of a number of members carried by said belts, and themselves serving to carry the plows 23, 23 and 24, 24. A similar agitator-conveyor, not shown in Fig. 4, is located above the floor 2. Same is mounted on end pulleys 25 and 26 and intermediate idlers 21, the pitch line of the belts is shown at 28, other details of said agitator-conveyor are not shown. Power from an external source is communicated through the pulley 29. The direction of movement of the belts is shown by arrows. An elevating-conveyor 30, adapted to lift material and deliver it above the member 2; is mounted within the passage 12 on the pulleys 3| and 32; 33 is a pulley on the shaft which carries 32 adapted to drive said conveyor; 34 is an apron forming the upper boundary of the induction passage I2; 35, 35 are glazed windows. In Fig. 8 the members I and I" replace the members I and 9 of Fig. l.

In addition to the parts shown, heat insulation should be applied to external hot surfaces wherever practicable.

In operation, wet material is delivered, e. g., by a conveyor, to near the left-hand edge of the member 6. It is stirred and moved to the right by the plows or the like 23 and 24 carried by the endless belts l8, until it falls over the right-hand edge into the bottomof the passage I2. Thence it is lifted by the conveyor 30 and dropped onto the member 2, whence it is moved, with stirring, to the left by the plows carried by the belts 28, until it falls over the left-hand edge of 2 into the passage ll.

' accumulate there to some extent as shown at C. Removal is made, continuously or otherwise, preferably, however, leaving an accumulation more'or less as figured at C.

Meanwhile, heat, of relatively high temperature, that is to say much above the aqueous boil-. ing point, is applied under the member 2 so as to boil water out of the still wet material upon it. The resulting steam performs two functions: It heats the under side of the member 6 so as to induce evaporation of water from the layer of material on said member, and it displaces air downwardly in the passages I l and I2. It has, moreover; a continuous scavenging effect on air which is brought into the passage I2 with wet material. It accomplishes these functions in part owing to the more than double weight of air compared with steam (and even greater weight when expanded to steam temperature) but it also mixes with said air; and the steam generated above the mixture, and lighter than same, forces said mixture outwardly. I

This action operates to reduce the air in the chamber to a minimum, and, save for discon It may conveniently be allowed to Li I tinuity' of operation, to keep it at such. This venting of the air is essential in order for the temperature of the steam condensing under the member 6 to approach the boiling-point, the condition governing such temperature being the partial pressure of the steam in the steam-air mixture. If I know, said partial pressure I can read from the steam-tables what said condensing temperature is, or, knowing the temperature, I can read off the accompanying partial pressure.

Once the apparatus is upfto a steady working moting the above described scavenging of airfrom ascending wet material.

My apparatus is peculiarly applicable for largescale drying of material which is very wet to start with and which does not require to be fully dried at the finish. Materials like wet bark. and the like, which often contain over 60% of water and which make excellent fuel when dried down to a residue of are cases in point.

The material in the first effect (on the plate 6) requires to be exposed to the air. It may, when desired, be exposed to forced ventilation to increase the rate of drying.

Heat may obviously be applied to the plate 2 by steam under pressure, or hot furnace-gases, or gas burnt by surface combustion, may beused directly under the plate 2, in which case the chest I beneath it may be omitted. Such a procedure requires precautions to be observed against warping said plate 2. A good heating medium for the purpose is the vapor of a highboiling substance, e. g., aniline, diphenyl or/and diphenyl oxide or the like.

The curbed holes 8 may be more numerous than shown and be greatly reduced in aggregate area, in which case the individual deflectors may be omitted without serious drawback.

My method of isolating material in an atmosphere of steam while maintaining passages open to the air may be used irrespectively of the object of such isolation. The method may be used in connection with the drying of webs, e. g., paper, the partially dried web being brought up into the steam-chamber, through a passage as I2, dried therein in any way, as on ordinary cylinder driers, and the resulting steam employed either in other cylinders, or, with intermediate compression, in the same ones which have caused its generation. In this case the drying is not compound. The web may be removed from the steam-chamber downwardly through a passage as H. Or, a substantially steam-tight induction or eduction member may be employed to admit or withdraw the web and a downwardly-extending passage be employed for its eduction or induction as the case may be.

The steam utilized for causing drying is derived from the upper portion of the enclosed chamber, and the gas-contaminated steam is rejected from the lower part of same.

While it is usually convenient to treat the same material in different stages in my two eifects, the latter may be worked independently on different lots.

It will be seen that the apparatus described, while illustrative, is by no means limitative of the invention, which may be efiectuated in various ways within the scope of the claims. The conveyors, agitators, plows and scrapers are especially subject to variation if only on account of differences in the physical condition of the mate rials to be treated.

While features of my invention may be employed, as above, in connection with the drying of.continuou's sheets, as paper, the'particular assembly described is for use with material in disconnected pieces, e. g., bark, wet wood waste, sand and gravel, coal, lignite, bagasse and the like. For the purposes of this application I denominate these as lump materials.

I claim:

1. In a drying apparatus, a structure which provides an aerated preheating and preclrying pan, a primary heating compartment substantially isolated from the atmosphere comprising steam space and material receiving space which extends to and is in part defined by. the exterior of said pan, so that preheating and predrying on said pan are accomplished through indirect heating by steam in 'the steam space, said structure having within said steam space a depressed pocket section of substantial area into which condensed steam is received and collected;

- means by which such collected condensed steam is passed out of the apparatus; means for passing material, which has been predried on the aerated pan, from the latter out of the atmosphere into the primary heating compartment, said latter means being so constructed as, under working conditions, to permit some egress of steam therethrough in counter-current with the in-moving material, whereby air is scavenged from said material, while at the .same time opposing resistance to said egress; means for heating the material within the primary compartment to efiect further drying of the same with accompanying transformation of moisture into steam, and means for passing dried material from said compartment out of the apparatus.

2. In drying apparatus, two members, an upper one adapted to carry material to be dried in contact with the atmosphere, and a lower one adapted to carry material inside a chamber of which said upper member forms an upper boundary, inlet and discharge passages extending downwardly from said chamber, means for supplying material to be dried to the upper surface of the upper member, for moving it over said surface and over the edge of same to a level lower than said lower member, and upwardly through the said inlet passage into said chamber, and then over said lower member to said discharge passage, and for heating'said lower member.

3. In drying apparatus, a chamber, a member, adapted to carry material, the lower surface of which forms an upper boundary of said chamber, a.second member, adapted to carry material, forming a floor in said chamber, a deflector, adapted to hinder condensate which forms'on the under side of the first member from falling onto material on the second member, having curbed holes adapted to permit interchange of fluid between the spaces above and beneath said deflector.

ERNEST-ARTHUR LE SUEUR.

LII 

